Lenovo Group hasn't had an easy time since its takeover of IBM's PC division, and its <A HREF="http://www.cio.com/blog_view.html?CID=23849">removal from the main index of the Hong Kong stock exchange</A> is just the most recent sign of trouble for the company. The world's third-largest PC vendor will formally be removed from the Hang Seng Index on Sept. 11, according to HSI Services, replaced by Taiwanese mobile phone maker Foxconn International Holdings. Losing its place on the index won't affect Lenovo's operations, but it could send its stock lower. And it's a small humiliation for the company, which was expected to be a major technology component of the Hang Seng.